Social factors, including family, parent-adolescent, and parent variables are influential in the development and continuation of adolescent substance abuse. Furthermore, research indicates that parents play a critical role in the successful treatment of adolescent drug problems. However, getting parents involved in the adolescent's treatment is a complex and difficult process that has rarely been explored in research studies. Building upon the investigator's and team's previous research, this study is designed to examine how therapists engage and retain parents in family-based adolescent drug treatment. Using existing therapy process theory, some of which has been generated and tested by the investigative team, this study aims to identify 1) the link between the parent- therapist alliance and retention in treatment, and 2) specific therapist interventions that build the parent-therapist alliance. To accomplish these goals, this study proposes to re-code existing videotapes and transcripts and to identify key aspects of the therapist-parent relationship that are hypothesized to predict retention in family therapy. Thus this investigation seeks to identify specific interventions and in-session processes that predict treatment retention with an ethnically diverse sample of adolescents and their parents. Research that can illuminate the clinical interior of therapy is fundamental in developing, improving, and disseminating effective interventions. Families that Dropout (attended less than 8 sessions) and Complete (attended more than 8 sessions) therapy have been selected from the archives of three empirically, supported family therapy models. Trained graduate student raters will identify (1) therapist support interventions and (2) therapist parent alliance quality and elements from videotapes and transcripts of actual manual-guided sessions from controlled clinical trials. HLM analyses will enable a comparison of differences in the trajectories of therapeutic processes between Dropouts and Completers.